Live-bottom bin



Jan. 14, 1964 Filed March 20, 1961 A. E. PEARCE ETAL LIVE-BOTTOM BIN 2Sheets-Sheet l Y aw LIVE-BOTTOM BIN 2 Sheets-Sheet 2 Filed March 20,1961 A: PAT/426E KENNETH L. .7090! m m W Maw irme/w United States Patent3,117,671 LIVE-BGTTQM ElN Albert E. Pearce, Summerville, and Kenneth 1..Jordan,

North Charleston, S.., assignors to West Virginia Pulp and PaperCompany, New York, N.Y., a corporation of Delaware Filed Mar. 29, 1951,Ser. No. 97,981 Claims. (Cl. 2%9-106) This invention relates to storagebins and like containers for bridgeable materials, such as chips,shavings, bark, and other fibrous materias, or mineralogical materials,that are readily flowable when not compacted, yet are interlocking andself-supporting when under pressure, and relates particularly toso-called live-bottom storage containers provided with rotatable rollsacross the bottoms thereof.

The materials to be stored in the live-bottom bin of this inventionpossess potentially inter-adherent surfaces creating the distinctive andcritical property, when compacted, of forming a concave, self-supportingstructure above an underlying void at the bottom outlet of the bin. Suchmaterials are commonly identified as bridgeable and present manydifficulties in handling and metering.

The particular bridgeable material for which the bin of this inventionis especially useful is the bark removed from pulpwood used in theproduction of paper and paperboard. Citing southern pine, such as slashpine, as an example, it is commonly estimated that A; of the rawpulpwood weight is bark at a natural moisture content of about %35%.During the debarking operation, Water is often sprayed onto the pulpwoodlogs to lubricate their passage over steel surfaces and to wash awaysand and dirt. Use of spray water increases the moisture content of thebark issuing from a typical barking drum to about This fairly wet barkis generally burned as a source of power in the more modern pulp mills.In handling the bark for this purpose. It may be sent to rough storageand thence to a power boiler, it may be delivered directly to theboiler, or it may pass, enroute to the boiler, through a hammermill typeof attrition machine which reduces overly large pieces to a moremanageable size. After such shredding, slabs or pieces of wood, up toone or two feet in length or more, may be left as oversize pieces.

Silos or storage bins which discharge sideways and have screwdischarging devices, drag chain devices, or rotating rolls forminglive-bottoms have been developed in the prior art for storage andmetering of some bridgeable materials. Live-bottom bins having rotatingrolls as the only bottom retaining surface and which discharge directlydownwards are also known. Nevertheless, livebottorn bins are generallytroubled with problems of handling and disposition of oversize piecesand with repairs caused by jamming of oversize pieces between the rollsor between the stationary and moving parts. When such jamming occurs, itis a common characteristic of live-bottom bins in the prior art thatrepairs or replacements to damaged screws, rolls, etc., are expensiveand time-coneuming because the material in the bin must usually bedislodged or removed manually before the feed devices may be approachedfrom above for repairs or replacement.

The objects of this invention are to provide means in a live-bottom binfor classifying oversize pieces from acceptable material, for ejectingthe oversize pieces from the bin, for delivering the acceptable materialin a uniform manner, at a desired rate, and in a fragmented state todisposal means, and for replacing or mechanically repairing the rotatingrolls in a simple and inexpensive manner.

In the accompanying drawings:

FIGURE 1 shows, schematically, a side view of a small live-bottom barkbin constructed in accordance with the principles of this invention andconstituting a particular working embodiment of the invention.

FIGURE 2 is a plan view, somewhat enlarged, showing the rolls comprisingthe live-bottom of the bin taken along line 2-2 of FIGURE 1 in thedirection of the arrows.

FIGURE 3 is a vertical sectional view of a portion of the bin, takenalong line 33 of FIGURE 1 in the direction of the arrows and showingbark in the bin.

FIGURE 4 is a cross-sectional view of a portion of the bin, taken alongline 4-4 of FIGURE 3 in the direction of the arrows.

FIGURE 5 is an enlarged cross-sectional View of the live-bottom area ofFIGURE 4.

As shown in the drawings, storage bin 10 has Walls 11 sloping outwardlyat the bottom to help prevent excessive arching or bridging of the bark12 which is fed into the open top of the bin from a conveyor. Four steelrolls 13, 14, 15, '16, which can be made of pipe, are rotatably mountedparallel and at equal distances apart at the bottom discharge opening 17(FIG. 4). The rolls are supported by pillow block bearings =18 on eachside thereof which are bolted on horizontal frame member 19 which issupported by legs 20. Bearings '18 are so located as to be accessiblefrom the outside of the bin. The rolls 13, 14, 15, 1d are powered by avaridiive unit 21 and a reducer 22 through conventional sprocket andchain drive as shown which rotate the rolls all at the same speed and inthe same direction. Reversing mechanism (not shown) may be provided forchanging the direction of rotation of the rolls.

Four cleats or ribs 23 of angle iron are rigidly attached along thecircumference of the rolls 13, 14, 15, 16 in each of three evenlystaggered groups, apart and parallel to the longitudinal axes of therolls, as shown in FIGURES 2 and 3. The cleats of each roll preferablyare out of phase with the cleats of each neighboring roll by a maximumamount, leaving a clearance between a cleat 23 and an opposing rollsurface and a larger clearance where bare rolls are opposed. The cleats23 obviouslycan take the form of other kinds of projections, such aspins, spikes, prongs, or the like for providing a rfiing action. Theelongated slots 24 between the rolls 13, 14, 15, 16 vary in shapeperiodically and rapidly with rotation of the rolls.

The staggered pattern of cleats on an individual roll decreases theamplitude of periodic rotational stresses on the rolls but is notessential to the invention. If the rolls 13, 14, 15, 16 are stopped, nodilhculty is experienced with unwanted escape of bark because thebridgeable characteristics of the bark 12 cause arch-like structures toform above the slots 24 almost immediately after stoppage of the rolls.

Acceptable bark 25 which has fallen through the slots 24 is caught andremoved by horizontal conveyor Z6 (FIG. 1). Slabs of bark, logs, orother wood fragments of overly-large size 27 (FIG. 5), are selectivelyrejected at one side of the bin through the left reject slot 28 abovethe side roll 16 when all of the rolls 13, 14-, 15, 16 are rotating inthe direction of rotation indicated by the arrows in FIGURE 5, orthrough the right reject slot 29 above the side roll 13 if the directionof rotation is reversed. An extension of the bin walls 11 by way ofvertically adjustable panel members 3t can be used to control the Widthof the reject slots 28, 2? through which rejected material 27 must pass.While the invention is operable with reject slots 23 and 29 of a fixedwidth (as long as they are wider than slots 24 between the rolls), thepanels 39 are a major control feature of the invention. The panels 3% asshown in FIGURE 5 are located inside two of the bin walls 11 at thebottom thereof and adjacent inverted channel members 31 which are weldedto the outside of such walls. The shanks of bolts 32 are passed throughmatching narrow vertical slots in the sides of inverted channel members31 and walls 11 and through holes in panels 3%. Wing nuts 33 arefastened on the threaded ends of bolts 32 to hold the panels St) inplace and this arrangement permits adjusting the panels up or down bysliding the bolts up or down in the narrow slots in the sides of theinverted channel members 31 and walls 11.

'Preferably, panels 39 are located directly above the axes of theoutermost rolls and thus provide reject slots 28 and 2h over the axes ofsuch rolls.

Accordingly, each reject slot is so positioned as to accept rejectmaterial that is flowing directly toward it in a horizontal path levelwith the reject slot opening. if the reject slot is inboard of the axisof an outermost roll, the flow of reject material reaches the rejectslot opening while it is traveling upwardly toward the top of the rolland at an angle to the reject slot opening. As

a result, some of the material small enough to pass through the slot isnot ejected as early as it might because of being directed upwardlyagainst the top of the reject slot and falling back into the bin.

Location of a reject slot slightly outboard of the axis of an outermostroll is a workable alternative but the reject slot must be above theroll and not at one side of the roll in order to avoid the wedgingaction of reject material between the roll and a side of the bin.

It is quite obvious that the reject slots 28 and 29 should always bewider than slots 24 between the rolls, yet not so wide as to allow anexcess of material to pass through. As the level of material in the bindrops, the pressure at the bottom from the weight of material decreasesand the bridging effect at the reject slots becomes less pronounced.Therefore, it may be advisable to adjust the reject slots to a narrowerwidth when the level in the bin reaches certain lower limits.

When the bin is wholly or partly filled with a bridgeable material suchas bark, the slots 28, 2 are solidly packed from the roll surfacesupwards by the compacted bark which easily maintains a vertical surfaceor curtain a the rolls toward the direction of rotation of the rolls,the

last roll 16 in FIGURE 5 receiving the rejected pieces 27 from the otherthree rolls. The oversize pieces 27, together with a relatively smallquantity of smaller pieces are directly impelled by the cleats of thelast roll 16 and are forcibly ejected through the 'bark curtain at theleft reject slot 28. The bark beyond the cleat tips, possessing lowermomentum, cannot break through the bark curtain extending downwards fromthe left adjustable slot control panel 39 and the arm of the left chanel31 at the upper side of the left vertical reject slot 28. Because thebark in this region is compressed, possessing depth in a horizontaldirection and upwards into the bin, it has considerable strength toresist rupture and deformation. However, a relatively large and solidreject, such as a small log, can be given su-fficient momentum by directcontact with the cleats 23 of the last roll 16 to disrupt and breakthrough the bark curtain. Accordingly, the bin can act as an effectiveclassifier if separate collecting means are provided for the rejectedpieces, since only a very small percentage of the acceptable smallerpieces are permitted to pass through the reject slots.

The existence of the bark curtain at the reject slots 23, 29 also tendsto create a back pressure upon the entire system so as to increase thepassage of acceptably sized material through slots 24.

By means of this invention bark can be fed at a fairly uniform rate, itbegins to feed immediately each time the rolls are started, and thebottom seals itself off each time the rolls are stopped.

The bin or" this invention will handle rough, unhogged bark veryefficiently. The large pieces of bark and broken pulpwood which can notpass through the slots are conveyed from one roll to the next, beneaththe bark, until the reject slot is reached. The accessible roll bearingspermit easy removal of the rolls from below and installation ofreplacement rolls. Further minor repairs to the rolls, when needed, canbe done directly from the bottom of the bin without emptying the bin.When a damaged roll is removed from the live-bottom layer of the fullbin, the bark in the bin above simply falls through the greatly enlargedslot until an arched tunnel structure has formed in the bark above theopening and this arched condition remains stable as long as the rollsare not in motion.

Uneven distribution of the bark within the bin can be avoided byreversing the rotational direction of the rolls. The rotating rollscause the bark to increase in height more rapidly on the side toward thedirection of movement of the tops of the rolls 134.6 when the rolls areoperated in one direction for a protracted time.

While there has been described a preferred embodiment of this invention,it will be understood that the invention is not limited thereto since itmay be otherwise embodied within the scope of the following claims.

What is claimed is:

1. A live-bottom bin for storing, classifying, and dispensing desiredquantities of bridgeable particulate material having varying shapes andsizes, comprising:

(a) a container having a bottom discharge opening whose cross section isat least equal in area to its top cross section and wall means forretaining bridgeable material over the entire bottom area,

(b) a plurality of rotatable cylindrical rolls which are alignedsubstantially horizontally, in mutually parallel relationship, andspaced appreciably apart to define elongated slots therebetween, saidrolls substantially occupying said bottom discharge opening andsupporting the bridgeable material in the container,

(0). rows of cleats affixed to said rolls which are axially aligned inmutually parallel rows and which extend radially from the surface of anyroll for raking and agitating the bridgeable material when the rolls arerotating, the rows of cleats on any roll being so positioned as to beout of phase with the rows of cleats on the adjacent rolls to eitherside,

(d) power means operable to rotate the rolls so that the upper surfacesof said rolls move all in the same direction toward a side of the bin,whereby as the rolls are so rotated bridgeable material too large topass through the slots between the rolls is conveyed across the top ofthe rolls toward said side of the bin, while the remainder of thebridgeable material passes downward through the slots between the rolls,and

(e) reject classification means at said side of the bin:

(1) which are substantially parallel to the longitudinal axes of therolls,

(2) toward which the upper surfaces of the rotating rolls move whenrotated,

(3) and against which the bridgeable material in the bin is urged by therotating rolls to create having considerable strength to resist ruptureand deformation, whereby relatively large and solid objects possessingsuflicient momentum are passed through said curtain and are then ejectedfrom the bin through the reject classification means, while materialsmall enough to be downwardly dispensed between the rotating rolls issubstantially prevented by said curtain from being ejected from the bin.

2. The live-bottom bin of claim 1 in which a second rejectclassification means is located at the side of the container oppositethe first reject classification means and the power means is equippedwith reversing mechanism to rotate the rolls all together toward thesecond reject classification means.

3. The live-bottom bin of claim 1 in which the two opposite sides of thecontainer slope inwardly toward the top.

4. The live-bottom bin of claim 1 in which the top of the elongatedopening forming the reject classification means is vertically adjustablein parallel relation to the upper surface of the roll which forms thelower boundary of said opening, whereby the height of the rejectclassification means may be varied in order to control the rigidity ofthe curtain for regulation of the size of the ejected objects andcompensation for variations in height of the stored bridgeable material.

5. The live-bottom bin of claim 1 wherein attachment means are providedwhich permit any roll selected from the rolls comprising the live bottomto be removed downwardly while the bin contains a substantial quantityof bridgeable material.

References Cited in the file of this patent UNITED STATES PATENTS935,630 Abernathy Oct. 5, 1909 1,500,275 Shick July 8, 1924 2,743,813Erickson May 1, 1956 2,826,300 Ross Mar. 11, 1958 2,907,445 Jones Oct.6, 1959 FOREIGN PATENTS 451,452 Germany Oct. 20, 192 7 870,376 GermanyMar. 12, 1953

1. A LIVE-BOTTOM BIN FOR STORING, CLASSIFYING, AND DISPENSING DESIRED QUANTITIES OF BRIDGEABLE PARTICULATE MATERIAL HAVING VARYING SHAPES AND SIZES, COMPRISING: (A) A CONTAINER HAVING A BOTTOM DISCHARGE OPENING WHOSE CROSS SECTION IS AT LEAST EQUAL IN AREA TO ITS TOP CROSS SECTION AND WALL MEANS FOR RETAINING BRIDGEABLE MATERIAL OVER THE ENTIRE BOTTOM AREA, (B) A PLURALITY OF ROTATABLE CYLINDRICAL ROLLS WHICH ARE ALIGNED SUBSTANTIALLY HORIZONTALLY, IN MUTUALLY PARALLEL RELATIONSHIP, AND SPACED APPRECIABLY APART TO DEFINE ELONGATED SLOTS THEREBETWEEN, SAID ROLLS SUBSTANTIALLY OCCUPYING SAID BOTTOM DISCHARGE OPENING AND SUPPORTING THE BRIDGEABLE MATERIAL IN THE CONTAINER, (C) ROWS OF CLEATS AFFIXED TO SAID ROLLS WHICH ARE AXIALLY ALIGNED IN MUTUALLY PARALLEL ROWS AND WHICH EXTEND RADIALLY FROM THE SURFACE OF ANY ROLL FOR RAKING AND AGITATING THE BRIDGEABLE MATERIAL WHEN THE ROLLS ARE ROTATING, THE ROWS OF CLEATS ON ANY ROLL BEING SO POSITIONED AS TO BE OUT OF PHASE WITH THE ROWS OF CLEATS ON THE ADJACENT ROLLS TO EITHER SIDE, (D) POWER MEANS OPERABLE TO ROTATE THE ROLLS SO THAT THE UPPER SURFACES OF SAID ROLLS MOVE ALL IN THE SAME DIRECTION TOWARD A SIDE OF THE BIN, WHEREBY AS THE ROLLS ARE SO ROTATED BRIDGEABLE MATERIAL TOO LARGE TO PASS THROUGH THE SLOTS BETWEEN THE ROLLS IS CONVEYED ACROSS THE TOP OF THE ROLLS TOWARD SAID SIDE OF THE BIN, WHILE THE REMAINDER OF THE BRIDGEABLE MATERIAL PASSES DOWNWARD THROUGH THE SLOTS BETWEEN THE ROLLS, AND (E) REJECT CLASSIFICATION MEANS AT SAID SIDE OF THE BIN: (1) WHICH ARE SUBSTANTIALLY PARALLEL TO THE LONGITUDINAL AXES OF THE ROLLS, (2) TOWARD WHICH THE UPPER SURFACES OF THE ROTATING ROLLS MOVE WHEN ROTATED, (3) AND AGAINST WHICH THE BRIDGEABLE MATERIAL IN THE BIN IS URGED BY THE ROTATING ROLLS TO CREATE WITHIN THE BIN A PILE HAVING A SURFACE OF REPOSE SLOPING AWAY FROM SAID SIDE OF THE BIN, SAID REJECT CLASSIFICATION MEANS BEING AN ELONGATED OPENING WHICH IS LOCATED ABOVE AN OUTERMOST ROLL AND HAVING THE UPPER SURFACE OF SAID OUTERMOST ROLL AS A LOWER BOUNDARY THEREOF, SAID ELONGATED OPENING BEING OF GREATER WIDTH THAN ANY SLOT BETWEEN THE ROLLS YET SUFFICIENTLY NARROW TO SUPPORT A SUBSTANTIALLY VERTICAL CURTAIN OF BRIDGEABLE MATERIAL WITHIN THE BIN IN FRONT OF SAID ELONGATED OPENING, SAID CURTAIN HAVING CONSIDERABLE STRENGTH TO RESIST RUPTURE AND DEFORMATION, WHEREBY RELATIVELY LARGE AND SOLID OBJECTS POSSESSING SUFFICIENT MOMENTUM ARE PASSED THROUGH SAID CURTAIN AND ARE THEN EJECTED FROM THE BIN THROUGH THE REJECT CLASSIFICATION MEANS, WHILE MATERIAL SMALL ENOUGH TO BE DOWNWARDLY DISPENSED BETWEEN THE ROTATING ROLLS IS SUBSTANTIALLY PREVENTED BY SAID CURTAIN FROM BEING EJECTED FROM THE BIN. 